Cartridge fuse assembly



Aug. 24, 1965 R w, vos 3,202,787

CARTRIDGE FUSE ASSEMBLY Filed Oct. 25, 1962 wi d wig? R/0R AR 7) (PR/OR ART) 1 (PR o R A R 7T 6 (PR/OR AR T) I KG!!! IN VEN TOR y lQ/CHAR'D w. I/OSPE/Q ATTOR EY of the insulating tube.

United States Patent 3,202,787 CARTRIDGE rush ASSEMBLY Richard W. Vesper, Greenwich, Conn, assignor to Inter- This invention relates to cartridge type electrical fuses and more particularly to cartridge type electrical fuses employing knife blades.

Fuselinks in present cartridge fuse assemblies are attached to knife blades by means of hollow steel studs. This assembly is then placed Within an insulating tube. The two steel studs which secure the two knife blades to the fuse link are securely held in place by four copper plated drive screws which are positioned in both ends of the cavity of each stud through drilled holes in the walls The conventional cartridge fuse has two fuse caps, two steel studs, four copper plated drive screws, two knife blades, one fuse link and one tube. My invention reduces the number of parts in cartridge fuse assemblies from twelve to six; namely, two fuse caps, two knife blades, one fuse link, and one tube. My invention also provides a tighter and more secure hold on the fuse link than was achieved by the rather loose engagementof the steel studs heretofore used.

It is an object of my invention to provide a cartridge type fuse which is simple and economical to manufacture.

Another object is the provision of means for securely holding fuse links in cartridge type fuses in order to prevent any possible twisting or deformation of the link due to mechanical stresses.

One of the structural features of this invention is the provision of an insulating tube for cartridge type fuses having keyways broached on the interior of the tubular wall for securely holding a fuse link and knife blade assembly in place.

Another feature is the provision of knife blades for cartridge type fuses having flanges which provide extra mechanical strength and insure positive gripping of the knife blades with the tubular wall of the tube in which it is inserted.

Still another feature of this invention is the provision of an elastic circular cross-sectioned tube for cartridge type fuses which can be deformed to an elliptical cross-section so that a fuse link assembly may be easily inserted into it while deformed. The deforming force is then released so that the fuse link assembly is firmly gripped by the tube walls.

I The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a plan view of a conventianal fuse link;

FIGURE 2 is an end view of the fuse link of FIG- URE 1;

FIGURE 3 is an end view of a conventional slotted fuse FIGURE 4 is a side elevational view of the cap of FIG- URE 3;

FIGURE 5 is a side elevational view of a tube for cartridge type fuses in accordance with my invention;

FIGURE 6 is an end view of the tube of FIGURE 5;

FIGURE 7 is an end view of a conventional knife blade;

FIGURE 8 is a plan view of the knife blade of FIG- URE 7;

FIGURE 9 is a plan view of a knife blade in accordance with my invention;

FIGURE 10 is an end view of the knife blade of FIG- URE 9; and,

FIGURE 11 is a longitudinal cross-sectional view of an assembled cartridge type fuse in accordance with my invention. 1'

Refer now to FIGURES land 2 which illustrate a con ventional fuse link. The flat rectangular fuse linkl has fuseable sections 2, 3, and 4 which are formed by the rectangular holes 5, 6, and 7, respectively. Holes 8 are provided for connecting the fuse link to suitable knife blades having complementary raised dimples (item 15, FIGURE 8). The fuse link is a calibrated lentgh of conductive material whose resistance is so chosen that when a certain minimum current passes through it, not enough of the heat caused by the current can be released by radiation and the fuse link will melt.

Refer now to FIGURES 3 and 4 which illustrate a conventional slotted end cap. The cap 9 is provided with flanged ends ltlwhich are crimped onto the tube to which the cap 9 is to be attached. The cap is also provided with a slot 11 so that it can be fitted over a fuse knife blade.

FIGURES 5 and 6 illustrate a hollow insulating member in accordance with this invention. The tube 12 is made of insulating material such as oil impregnated paper and has two keyways or grooves 13 oppositely disposed. The tube 12 is elastic so that it may be deformed to an elliptical cross-section and, upon release of the deforming force, tends to return to its original shape. The keyways 13 may be formed in a broaching operation though other means may be used to form them. The tube crosssection need not be circular, but may be any desired shape which will suit the purpose to be achieved. The tube 12 permits the easy insertion of fuse link assembly end first with the end of the link parallel to the longer axis of the ellipse formed by the cross-section of the tube when it is deformed. The keyways 13 prevent the inserted fuse link assembly from turning in the tube since the sides of the keyways prevent rotational movement of the fuse link assembly because the knife blades thereof are held in the keyways.

The conventional knife 14 is shown in FIGURES 7 and 8 and has a raised dimple 15 which is produced by a coining operation which also causes the depression 16 to be formed. A knife blade in accordance with my invention is shown in FIGURES 9 and 10. The knife blade 17 has flanges 18 which are formed during a coining operation in which the raised dimple 15 is formed. The overall dimension of the knife blade across flanges 18 is preferably slightly greater than the normal interior cross-sectional dimension of the tube 12 including the depth of the grooves 13 so that when the tube is released from the deforming pressure it will tend to return to its normal shape thus gripping flanges 18.

FIGURE 11 is a cross-sectional view of an assembled cartridge type fuse comprising the fuse link 1, tube 12, caps 9, and knife blade 17. It can be seen that the fuse link is connected to the knife blades by means of the raised dimples 15 which are inserted in the holes 8. A

rigid connection is achieved by soldering the raised dimple to the fuse link. The elastic stress of the tube 12 to form a perfect circle insures a snug fit of the knife blades 14 in the keyways 13. The caps 9 are rigidly attached to the tube 12 by being crimped at 20, the crimped edge lapping over the inner shoulders of the flanges 18, thus forcing a portion of the tube inwardly as indicated at 21 to further insure a tight grip longitudinally onto the fuse link assembly.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

aeoeyrav 35 v I i What is claimed is: 1 wherein said hollow member has at least two such 1. A cartridge type electrical fuse comprising: grooves diametrically disposed and said knife blades have (a) a fuse link; flanged portions for reception in said grooves. (b) knife blades for supporting said fuse link, said 3. A cartridge type electrical fuse according to claim -blades having laterally disposed flanged'portions; 5 1 wherein said restricting means includes end caps re- (c) a hollow insulating member, said member being deceived over the ends of said hollow member with the edge formable and having at least one longitudinal groove portions of said caps crimped onto said member forcing therein parallel with the axis of said member and exa' portion of said hollow member to lap over a portion tending throughout the length of said member, means of said knife blades. disposing the edges of said flanged portions within 10 saidgrooves, the width of each said knife blade be- References Cited y the Examine! tween the outer edges of said flanged portions being TE STATES PATENTS greater than the inner Width of said hollow insulating member including the grooves thereof, whereby the r edges of said flanged portions are gripped by the walls 15 p Said groove; and, 2,981,787 4/61 Brautlgam et al. 17477 (d) end caps for enclosing both ends of said hollow FOREIGN PATENTS member, said end caps being crimped onto said mern- 32 7 44 4/34 Holland.

ber forcing a portion thereof inwardly in overlapping relation tothe inner ends of said flanged POItlOIlS. 20 BERNARD A GILHEANY, Primary Examiner 2. A cartridge type electrical fuse according to claim 

1. A CARTRIDGE TYPE ELECTRICAL FUSE COMPRISING: (A) A FUSE LINK; (B) KNIFE BLADES FOR SUPPORTING SAID FUSE LINK, SAID BLADES HAVING LATERALLY DISPOSED FLANGED PORTIONS; (C) A HOLLOW INSULATING MEMBER, SAID MEMBER BEING DEFORMABLE AND HAVING AT LEAST ONE LONGITUDINAL GROOVE THEREIN PARALLEL WITH THE AXIS OF SAID MEMBER AND EXTENDING THROUGHOUT THE LENGTH OF SAID MEMBER, MEANS DISPOSING THE EDGES OF SAID FLANGED PORTIONS WITHIN SAID GROOVES, THE WIDTH OF EACH SAID KNIFE BLADE BETWEEN THE OUTER EDGES OF SAID FLANGED PORTIONS BEING GREATER THAN THE INNER WIDTH OF SAID HOLLOW INSULATING MEMBER INCLUDING THE GROOVES THEREOF, WHEREBY THE EDGES OF SAID FLANGES PORTIONS ARE GRIPPED BY THE WALLS OF SAID GROOVE; AND, (D) END CAPS FOR ENCLOSING BOTH ENDS OF SAID HOLLOW MEMBER, SAID END CAPS BEING CRIMPED ONTO SAID MEMBER FORCING A PORTION THEREOF INWARDLY IN OVERLAPPING RELATION TO THE INNER ENDS OF SAID FLANGED PORTIONS. 